I mean corporation because in corporation capital ownership and direct participation in management are distinguished. Cf.: societe anonyme. 'Firm' = name / signature ... etymologically and financially and denote the 'ID' of a participant in an economy. Firm is the widest sense, it matches 'account' in the cryptosphere. On PoS as reinvention of corporation - exactly right, you nailed it - it is automation of corporation, call it so then ... it is NOT guaranteed that 'human being ultimately has the control' until there is some orthogonal to the PoS protocol ID verification protocol. Which inevitably involves off-chain ID validators. Involves TRUST, i.e. involves force. The 'hybrid' of PoW and PoS would then have three dimensions or coordinate axes - PoW, PoS and ID ver. The trick is to get to MORE efficient scheme of work, isn't it? Occams rasor cuts us otherwise. Long term investors willing higher SRI/ESG levels and public profile would rather choose outright centralized ledger which exist and are mainstream in enough electronic form, rather than 'hybrids'. Naturally 'hybrids' have worse performance vs the specialized solutions. Example.: a duck, it flies, swims and walks but flies worse than an eagle, swims worse than a dolphin and walks worse then a cheetah. Tradeoffs ... of hybridization. ( Note that I do not say that PoS as corporation-on-crypto is not possible to be better than centralized ledger corporation. But it is the end, not means to an end. The means is crypto, the end is corporation).